High current consumption with LPCOMP enabled

[GiulianoFranchetto]

Hi,

I'm currently testing LPCOMP with one of our nRF5340DK boards.

The power consumption of the LPCOMP seems way too big (around 140µA) once enabled with this conf:

nrfx_lpcomp_config_t config = {
		.hal    = {NRF_LPCOMP_REF_SUPPLY_2_8,
			   NRF_LPCOMP_DETECT_CROSS,
			   NRF_LPCOMP_HYST_NOHYST},
		.input  = (nrf_lpcomp_input_t) NRF_LPCOMP_INPUT_2,
		.interrupt_priority = NRFX_LPCOMP_DEFAULT_CONFIG_IRQ_PRIORITY
	};

The 140µA are from the LPCOMP alone, as there is no other functionnality enabled on that board (no CONFIG_LOG, no CONFIG_SERIAL ...)

If I #if 0 ... #endif all my code, the current consumption drops to < 10µA.

Is there a errata on the LPCOMP that could explain such large current consumption?

Can we reduce it programmatically?

Regards

Giuliano

[Edvin]

Hello,

What current consumption do you see on the LPCOMP? Can you please share the project that you use to measure the current consumption (the one containing the #if condition)? So that I can easily reproduce this and measure it?

BR,

Edvin

[GiulianoFranchetto]

Hello,

As said, I can measure an increase of 140µA when enabling LPCOMP, which seems like a lot.

I've attached the project with my answer.

lpcomp_test.zip

Regards

Giuliano

[GiulianoFranchetto]

Hi Edvin,

Any news on that subject?

Did you reproduce the issue?

Regards

Giuliano

[Edvin]

Hello Giuliano,

I have done the same measurements as you have done, and I see the same behavior. I don't why this is happening. I will try to speed up the process to figure out why it is drawing so much power. I agree that it is more than the expected amount.

Just while I ask around. Are you using a DK? If so, what version do you have? (I am testing on a 0.10.0 version).

[GiulianoFranchetto]

Hi Edvin,

We are indeed using the nRF5340 PDK.

I can't find a more specific version printed on the PCB. 

[Edvin]

Is there no white sticker on the large chip "in the middle"? 

By the way, when you built this sample, did you have to modify the NCS? I couldn't build it without adding the peripheral manually in the file zephyr\soc\arm\nordic_nrf\nrf53\Kconfig.soc:

// From line 66:
	select HAS_HW_NRF_WDT0
	select HAS_HW_NRF_WDT1
	select HAS_HW_NRF_LPCOMP

If you didn't, how do you compile your project?

BR,
Edvin

[GiulianoFranchetto]

Indeed, I had to add the configuration in the Kconfig of the soc.

Sorry for forgetting to mention that.

As for the version, I don't have the board right now. From what I remember, we bought the board months ago, so I guess this is the Engineering rev A version of the nRF5340 mounted on this board.

** EDIT ** The version is 0.8.0

Rgards

Giuliano 

[GiulianoFranchetto]

Hi Edvin,

A quick message to know if you've made any progress of that ticket, and if I can be of any help.

Regards

Giuliano

[Edvin]

There is still a discussion in an internal ticket that I created based on this point. Still ongoing testing. I will get back to you with updates as soon as I have a less diffuse idea on what's going on.

[Edvin]

Hello,

There are still internal discussions. My understanding is that there is nothing in NCS causing this, as the current consumption looks similar in a bare-metal implementation. I guess that is the current status.

BR,
Edvin

[GiulianoFranchetto]

Hi Edvin,

Thank you for your update.

Keep me posted!

Regards